Alexander’s husband is infertile, and traditional adoption wasn’t a viable option for this military family. Alexander decided to use embryos from another family to build her own.

Alexander started researching frozen embryo donations specifically for families hoping to adopt. She contacted the religious embryo adoption agency, Snowflake, and began the process, which included a home study, a full medical background check of the donating family, and photos of their children.

“This to me is the only clear choice—why would you deny them a chance at life?” Alexander said.

Cora and Max were created in 2006, adopted in 2009 and born in 2010.

With the growing popularity of in vitro fertilization, there is a surplus of more than 600,000 frozen embryos available.

Fertility patients are split over what to do with their unused embryos. According to a recent study, 54 percent want to keep them frozen for future use, 21 percent want them donated to research, and 7 percent want them donated to another couple.

Embryo adoption is on the rise, shooting up 25 percent last year. The choice can ultimately be more cost effective than egg donation.

Alexander's choice, though, came with challenges, starting with her Catholic faith.

The Catholic Church states that human life should not be created in a laboratory and cautions against embryo adoption.

“The Catholic Church said it's morally problematic. If at any time the church were to say no ... on embryo adoption, we would walk away from it,” she said.

"It's truly incredible to see what they have become. They were three embryos frozen in a freezer. We lost one in the process, but now we have two incredible children," she said.

Alexander says she hopes to go through embryo adoption again. She has limited communication with the children's genetic parents through her adoption agency. At many fertility clinics, though, embryo donations are anonymous.